Topological quantum phase transition of light

TL;DR

This paper theoretically investigates topological quantum phase transitions in a cavity QED lattice, identifying conditions for phase changes and the emergence of Majorana modes using topological invariants.

Contribution

It predicts the conditions for topological phase transitions in cavity QED systems and characterizes these transitions through winding numbers and symmetry considerations.

Findings

Topological phases emerge when Z2 symmetry is broken.

Majorana modes appear at the ends of the lattice in the topological phase.

Transition conditions are derived for three different model Hamiltonians.

Abstract

We study theoretically the topological quantum phase transition in Cavity QED lattice. We predict the condition for non-topological phase to the topological phase transition conditions for three different model Hamiltonians in cavity QED lattice. We study these topological quantum phase transition through winding number, which is a topological invariant quantity. We argue that the appearance of topological phase in these systems where the discrete Z 2 symmetry broken. We show that the non-topological state is the vacuum state of the system where each cavity contains fermionic type excitations from light-matter interaction whereas the topological state of system contains Majorana modes of excitations at the end cavity of the lattice.